System for controlling a clutch and/or a motor of a vehicle

ABSTRACT

The invention is directed to a system for controlling a clutch which is arranged between the motor of a vehicle generating a motor torque and the wheels of the vehicle. With this clutch, and in response to a drive signal, the force flow between the motor of the vehicle and the wheels can at least be reduced. The essence of the invention is that the drive signal of the clutch is formed in dependence upon a signal which represents a change of the motor torque of a specific extent. The invention is also directed to a system for controlling the motor of a vehicle with an adjusting element for influencing the motor torque which can be adjusted at least in dependence upon the detected command torque. When a specific extent of a change of motor torque is present, the execution of the command to adjust the motor torque is delayed. The essence here is that a clutch is arranged between the vehicle motor and the wheels of the vehicle and the delay is actuated in dependence upon a status signal representing the instantaneous operating state of the clutch.

RELATED APPLICATION

This application is a continuation-in-part application of patentapplication Ser. No. 08/767,065, filed Dec. 16, 1996 abandoned, andentitled "System for Controlling a Clutch and/or a Motor of a Vehicle".

BACKGROUND OF THE INVENTION

Automatic clutches or servoclutches are, for example, known from thetext entitled "Automotive Handbook", third edition, (1993), pages 538and 539 as well as from German patent application P 195 40 921(corresponding to International patent application PCT/DE 96/01347,filed Jul. 23, 1996). Automatic clutches in combination with electroniccontrol apparatus provide either an automated start from standstill or,together with a servo-actuated shifting mechanism, a fully automatictransmission. In such automatic clutches, the disengagement andengagement of the clutch is generally actuated via a servodrive.

In addition to such automatic clutches, automatic transmissions areknown wherein the transmission ratio can be changed in response to adrive signal. Such automatic transmissions can, in a manner known perse, be connected to the motor of the vehicle via a hydraulic converter.

It is known that the shifting pressure or the fluctuations in thedrivetrain occurring under these circumstances can be attenuatedutilizing the converter. The shifting pressure arises with the change ofthe transmission ratios. The converter can be bridged by a knownconverter bridge clutch or the bridge can be removed. At higher vehiclespeeds or in the upper gears of the transmission, this converter bridgeclutch is mostly engaged. In this way, slip losses of the torqueconverter are prevented and, in this way, the fuel consumption isreduced; however, the effect of the converter in attenuatingfluctuations in the drivetrain is not provided when the converter bridgeclutch is engaged. In addition, the slip of such converter clutches canbe controlled.

Furthermore, it is known to provide a motor control apparatus forcontrolling the motor of a vehicle by means of which the motor outputtorque is controlled, for example, in dependence upon the following:driver command, motor operating parameters and additional variablesrepresenting or influencing the operation of the vehicle. German patentpublication 4,321,333 discloses an electronic accelerator pedal systemwherein measures for reducing fluctuations in the drivetrain during thetransition from the overrun phase to the drive phase are provided. Thesemeasures include that the transition from the overrun phase into thetractive phase is detected and that, when a transition is detected, theexecution of the command of the driver for adjusting the power of theinternal combustion engine is delayed.

SUMMARY OF THE INVENTION

It is an object of the invention to optimize such systems for reducingthe fluctuations in the drive train.

The system of the invention is for controlling a clutch arranged betweena motor of a vehicle generating a motor torque (M_(mot)) and the wheelsthereof. The system includes: a first control apparatus for generating asignal (ΔM_(mot) and/or |ΔQ_(i) |) indicating a change of a specificamount of the motor torque (M_(mot)); a second control apparatus forforming a drive signal (P_(wk)) in dependence upon said signal(ΔM_(mot)) to cause the clutch to at least reduce the power flow betweenthe motor and the wheels; and, the signal (ΔM_(mot) and/or |ΔQ_(i) |)indicating whether one of the following is provided:

(a) a change of sign of the motor torque (M_(mot));

(b) an interruption or discontinuous reduction of the fuel metering tothe motor (|ΔQ_(i) |>SW); or,

(c) a resumption of fuel metering or an abrupt increase of the meteringof fuel (|ΔQ_(i) >SW) after said interruption or said abrupt reduction.

In a first embodiment, the invention proceeds from a system forcontrolling a clutch which is mounted between a vehicle motor, whichgenerates a motor torque, and the wheels of a vehicle. The force flowbetween the vehicle motor and the wheels can be changed via this clutchin response to a drive signal. That is, the force flow can, for example,at least be reduced or the rigid coupling between the motor of thevehicle and the wheels can be interrupted. The essence of the firstembodiment of the invention comprises that the drive signal of theclutch is formed in dependence upon a signal which represents a changeof a specific extent of the motor torque. This first variation of theinvention affords the advantage that a disengagement or a control of theconverter clutch is effected in time in advance of a significant changeof the output torque of the motor. In this way, the converter can remaincompletely engaged in the lower gears and must not be disengaged orcontrolled for reasons of comfort because of the drivetrain fluctuationswhich can possibly occur. This leads to a minimal loss of energy whichoccurs when the converter clutch is not completely engaged withoutreducing comfort.

In this variation, the signal, which represents a change of motortorque, can represent a change of the motor torque to be introduced bythe motor control and especially an abrupt change of motor torque.

The motor torque is, in general, controlled via a motor control and theclutch is controlled via a clutch or transmission control. It can beprovided that the signal, which represents a change of motor torque, isformed in the motor control and is supplied to the clutch control or thetransmission control.

The drive signal can be configured in response to a change (especiallyan abrupt change) of the motor torque which is to be introduced andrepresented by the signal. The drive signal can be so formed in reactionto this signal that the rigid connection between the vehicle motor andthe wheels is interrupted. Whereas this connection is rigid when theconverter clutch is engaged, this rigid connection can be disengaged viaa disengaged converter clutch (with or without slip).

In the second variation according to the invention, the inventionproceeds from a system for controlling a vehicle motor via an actuatingelement for influencing the motor torque which is adjusted at least independence upon the detected command of the driver. When a change of thedesired motor torque of a specific extent is present, the execution ofthe command (for example, driver command and/or tempomat/traveling speedcontrol) for adjusting the motor torque is delayed. The essence of thesecond embodiment of the invention is that a clutch is mounted betweenthe vehicle motor and the wheels of the vehicle and the delay isactuated in dependence upon a status signal representing theinstantaneous operating state of the clutch. This second embodiment ofthe invention affords the advantage that the delay of the desiredcommand is only then actuated when the converter clutch cannot executethe above-mentioned attenuation (for suppressing the fluctuations in thedrivetrain) because the converter clutch is engaged or is notsufficiently disengaged.

In this embodiment of the invention, it is advantageously provided thatthe above-mentioned status signal indicates the presence of at least oneof three operating states. The first operating state is characterized bya disengaged clutch and the second operating state is characterized byan engaged clutch. The third operating state is characterized by acontrolled clutch operation.

The motor torque is generally controlled by means of a motor control andthe clutch is controlled by means of a clutch or transmission control.Here, it is advantageous that the status signal of the clutch is formedin the clutch control or transmission control and is supplied to themotor control. The first operating state or third operating state(clutch not completely engaged) of the clutch are represented by thestatus signal. In response to this operating state, the delay executingthe driver command to adjust the motor torque cannot be carried out orcan be carried out only in the sense of shortening the delay.

For both embodiments, the extent of a specific torque change can be:

(a) a change in sign of the motor torque;

(b) an interruption or an abrupt or discontinuous reduction of themetering of fuel to the engine (for example, in reaction to a detectedoverrun operation of the engine) and/or;

(c) a resumption of the metering of fuel after an interruption or aftera reduction of the metering of fuel to the engine or an abrupt ordiscontinuous increase of the metering of fuel to the engine (forexample, after or at the end of the overrun operation).

As already mentioned, a torque converter can be bridged by means of theclutch or the clutch can be a servo-operated clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 is a schematic block circuit diagram of a first embodiment of thesystem of the invention for controlling a clutch arranged between thevehicle motor and the wheels of the vehicle;

FIG. 2 is a schematic block circuit diagram of a second embodiment ofthe system according to the invention;

FIG. 3a is a schematic detail block diagram showing the motor controlapparatus of the system of FIG. 2;

FIG. 3b is a flowchart showing the function of the block 1012 of themotor control apparatus of FIG. 3a; and,

FIGS. 4a to 4d are flowcharts showing the function of the transmissioncontrol apparatus of the system of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Elements performing the same function are identified by the samereference numerals in FIGS. 1 and 2. In FIGS. 1 and 2, a torqueconverter is identified by reference numeral 11 and is arranged betweena vehicle engine 10 and a transmission 12. The output torque M_(mot) ofthe engine 10 is supplied to the torque converter 11 via a drive shaft.The converter 11 is connected at its output to the wheels 13 via thetransmission 12. In this embodiment, the transmission 12 is an automatictransmission.

The operation of the vehicle engine 10 is controlled via the motorcontrol apparatus 101. Here, it is assumed that the driver issues adrive command. For this purpose, in FIG. 2, the position of anaccelerator pedal 1 actuated by the driver is transmitted to the motorcontrol apparatus 101.

The hydromechanically operating converter 11 can be bridged by theclutch 17. The clutch 17 can be completely or partially disengaged viathe drive signal P_(WK) or can be engaged. In addition to thetransmission ratio i of the transmission 12, the clutch or transmissioncontrol apparatus 16 controls the clutch 17. For this purpose,especially the motor rpm N_(mot) and the turbine or converter output rpmN_(T) are supplied to the clutch or transmission control apparatus 16.The motor rpm N_(mot) is detected via the sensor 14 and the converteroutput rpm N_(T) is detected by the sensor 15. To determine thetransmission ratio i, generally, the engine load or the drive command ofthe driver and the road speed are also used (not shown).

As mentioned, the converter bridge clutch 17 can be engaged ordisengaged and, in addition, a control of the clutch slip can beprovided which is derived, for example, from the ratio of N_(mot) toN_(T). Most automatic transmissions 12 today include such a converterbridge clutch 17 which is generally engaged in the higher transmissiongears in order to minimize increased fuel consumption caused byconverter slip. The disadvantage of this bridging is that the joltdamping or drivetrain vibration damping action of the converter 11 is nolonger present. Rapid changes of engine torque M_(mot) can then possiblybe transmitted almost entirely undamped to the drivetrain of the vehiclewhich causes the vehicle to tend to shake. This shaking is especiallynoticeable in the presence of two operating conditions of the engine:

(1) during the transition from normal operation (fired operation withnormal fuel metering) to known overrun cutoff (cutoff of the metering offuel in the overrun operation of the engine) and vice versa whenresuming the metering of fuel after an overrun cutoff of this kind. Theengine torque M_(mot) increases abruptly in these phases; and,

(2) when there is a sign change of the engine torque M_(mot) (transitionfrom overrun operation into the drive operation of the engine) becausehere the tooth flanks in the drivetrain change their contacts.

In both operating conditions, a distinct change of the motor torqueoccurs. These changes too can be predicted because these changes areinitiated by the motor control apparatus 101. As mentioned, theconverter clutch 17 can also be control driven, that is, the clutch isneither entirely engaged nor entirely disengaged in this control state.The clutch pressure is so controlled that the clutch grips with a lowslip. The advantage is that the energy losses in the converter aresignificantly lower than for a disengaged clutch; however, the dampingaction of the converter is at least still partially effective. However,it is disadvantageous that a certain higher consumption of fuel isunavoidable compared to the completely engaged clutch.

It is essential for the first embodiment of the invention shown in FIG.1 that the signal ΔM_(mot) is supplied to the clutch or transmissioncontrol apparatus 16 from the motor control apparatus 101. This signalΔM_(mot) indicates whether the motor control apparatus 101 controls themotor 10 so that a distinct change of the motor torque M_(mot) is to beexpected. In response to a significant change of the motor torqueM_(mot) indicated by the signal ΔM_(mot) (for example, in the sense ofthe above-mentioned two operating conditions), the clutch 17 is at leastpartially, and at best however, completely disengaged. When the motorcontrol apparatus 101 wants to carry out an overrun cutoff, a resumeoperation after an overrun cutoff or a distinct change in sign of themotor torque M_(mot) is to follow, then the motor control apparatus 101transmits data ΔM_(mot) to the clutch control 16 based upon which theclutch control 16 switches the converter clutch 17 from the engagedstate into the controlled or disengaged state (or from the controlledinto the disengaged state). When the action "overrun cutoff", "resume"or "engine torque sign change" actually is carried out, the converterclutch 17 is then no longer engaged so that the torque jump which occursin this way is damped in the drivetrain by the converter 11. FIG. 1 alsoshows the signal ΔQ_(i) which represents the change of the fuelmetering.

At this point, it is noted that a servo-operated clutch, known per se,can be used in lieu of the converter bridge clutch. In this case, theengaged servo-operated clutch is somewhat disengaged for a short time(low clutch slip) to dampen the jolt.

The status signal St is important for the second embodiment of theinvention shown in FIG. 2. This status signal St is conducted from theclutch or transmission control apparatus 16 to the motor controlapparatus 101 and indicates the operating state (engaged, disengaged,partially disengaged) of the converter bridge clutch 17. In the motorcontrol apparatus 101, a drivetrain damping is provided by means ofwhich the drive command expressed by the actuation of the acceleratorpedal 1 is not transmitted further immediately to the power control (forexample, the throttle flap). The problem with respect to drivetrainvibrations (for example, in response to a change of sign of the motortorque) can, in a manner known per se (see German patent publication4,321,333), be solved by means of a so-called EGAS-system by slowlypassing through the sign change region, that is, with a deceleratedpassing through this region.

The EGAS-system pertains to a configuration wherein, for example, theconnection from the accelerator pedal to the throttle flap of the engineis not mechanical but is via an electronic circuit so that the throttleflap is actuated electrically. However, if this function in the enginecontrol apparatus 101 is continuously active (that is, withoutdistinguishing whether the converter clutch 17 is engaged, partiallydisengaged or disengaged), then a double damping via the converter andvia the above-mentioned special EGAS function is obtained in the casewhere the controlled clutch is disengaged or partially disengaged. Theconsequences resulting from the foregoing can possibly be a relativelylethargic response performance of the vehicle to a movement of theaccelerator pedal.

According to the second embodiment of the invention, the status istransmitted to the motor control apparatus 101, for example, in the formof a three-step signal St (clutch disengaged, clutch controlled, clutchengaged). The described function "drivetrain damping" in the motorcontrol apparatus 101 is only activated when the state "clutch engaged"is present. In this way, damping occurs only once:

(1) via the function "drivetrain damping" in the motor control apparatus101 with the converter bridge clutch 17 engaged; and,

(2) via the converter 11 with an entirely or partially disengagedconverter bridge clutch 17.

The driver always has a similar response performance to the actuation ofthe accelerator pedal independently of the state of the converterclutch.

In lieu of switching off the function "drivetrain damping" in the motorcontrol apparatus 101 when the clutch is disengaged or partiallydisengaged, the clutch can continue to remain active but with other(weaker) parameters (reduced delay of the driver command) than in theengaged state of the clutch.

FIGS. 3a and 3b show the time-delay means for time-delaying the issuanceof a command torque signal when a change of the command torque signalexceeds a specific amount. The time-delay means is shown in the contextof a detail view of the motor control apparatus 101 of FIG. 2.

In FIG. 3a, the accelerator pedal signal α from the accelerator pedal 1is conducted to the block 1011. The block 1011 determines the desiredcommand torque M_(mot).1 from the signal α as well as from otheroperating parameters such as the engine rpm and/or the transmissionoutput rpm.

The desired command torque M_(mot).1 is supplied to the function block"drivetrain damping" referred to above (that is, time-delay 1012). Here,the desired command torque M_(mot).1 is modified in dependence upon thestatus signal St and, in this way, the modified desired command torqueM_(mot).2 is formed. This modification takes place in such a manner thatthe further transmission of the desired command torque M_(mot).1 takesplace in a time-delayed manner. The block 1012 can therefore beconfigured as a simple delay component having an adjustable delay.

The status signal St is outputted by the transmission control apparatus16 and indicates the presence of one of three operating states. Thefirst operating state (status signal St1) is characterized by an openedclutch and the second operating state (status signal St2) ischaracterized by a closed clutch and the third operating state (statussignal St3) is characterized by a controlled clutch operation.

The motor 10 is then controlled by block 1013 in such a manner that themodified desired command torque M_(mot).2 is realized.

FIG. 3b is a flowchart showing the function of the block 1012. After thestart step, the status signal St is read in. The function "drivetraindamping" is only then activated when the state "clutch closed" (statussignal St2) is present.

FIGS. 4a to 4d show the function of the transmission control apparatus16. After the start step, the signals ΔQ_(i) and/or ΔM_(mot) are readin. Then, in the next steps, a check is made as to whether a sign changeof the motor torque takes place and/or whether a marked (threshold valueSW) change (increase or reduction) of the fuel metering is provided viathe motor control apparatus 101. If this is the case, then the clutch isactuated in the direction "open", otherwise, the clutch remainsunaffected.

What is important here is that the signals ΔQ_(i) and/or ΔM_(mot)represent the fuel quantity to be metered, that is, the motor torque tobe adjusted. The fuel quantity or motor torque is therefore supplied tothe transmission control apparatus 16 before the marked changes in motortorque are initiated via the motor control apparatus 101. In this way,the clutch can be opened before changes of the motor torque occur.

The control apparatus 16 forms the drive signal (P_(wk)) in dependenceupon the signal (ΔM_(mot)) to cause the clutch to at least reduce thepower flow between the motor 10 and the wheels 13. The signal (ΔM_(mot)and/or |ΔQ_(i) |) indicates whether one of the following is provided:

(a) a change of sign of said motor torque (M_(mot));

(b) an interruption or discontinuous reduction of the fuel metering tothe motor (|ΔQ_(i) |>SW); or,

(c) a resumption of fuel metering or an abrupt increase of the meteringof fuel (|ΔQ_(i) |>SW) after said interruption or said abrupt reduction.

FIG. 4a shows the condition (a) by itself and FIG. 4b conditions (a) and(b). FIG. 4c shows condition (b) by itself and FIG. 4d shows condition(c) by itself.

Although the foregoing has been described with respect to an internalcombustion engine, it is conceivable that the system according to theinvention could also be applied to other drive units such as an electricmotor.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. A system for controlling a clutch arrangedbetween a motor of a vehicle generating a motor torque (M_(mot)) and thewheels thereof, the system comprising:a first control apparatus in theform of a motor control apparatus for generating a signal (ΔM_(mot))indicating a change of a specific amount of the motor torque (M_(mot))to be adjusted; said signal (ΔM_(mot)) indicating whether a change ofsign (+/-) of said motor torque (M_(mot)) representing transitions fromoverrun into drive operation is provided; and, a second controlapparatus for forming a drive signal (P_(wk)) in dependence upon saidsignal (ΔM_(mot)) to cause the clutch to at least partially open toreduce the power flow between the motor and the wheels when said signal(ΔM_(mot)) indicates that the change of sign (+/-) in said motor torque(M_(mot)) is provided thereby avoiding a jolt in the torque transmittedbetween said motor and said wheels.
 2. The system of claim 1, whereinsaid change is a discontinuous change.
 3. The system of claim 1, saidfirst control apparatus being a motor control apparatus configured tocontrol said motor torque (M_(mot)); and, said second control apparatusbeing a transmission control apparatus for controlling said clutch; and,said signal (ΔM_(mot)) being formed in said motor control apparatus andbeing transmitted to said transmission control apparatus.
 4. The systemof claim 1, said second control apparatus functioning to form said drivesignal (P_(wk)) in response to said change of said motor torque so as tochange said power flow so that the rigid connection between said motorand said wheels is interrupted.
 5. The system of claim 1, furthercomprising a torque converter interposed between said motor and saidwheels; and, said clutch being connected so as to bridge said torqueconverter.
 6. The system of claim 1, said clutch being a servo-clutch.